How to Fix CSRF Error in Gatsby

Stumped by a CSRF Error in Gatsby? This error is more common than you'd think, and the fix is usually simple.

Why This Happens

CSRF errors happen when your application can't verify that a form submission originated from your own site. Without proper token validation, the server rejects the request to prevent malicious cross-site attacks.

How to Fix It

The key is to generate a CSRF token per session and include it with each form submission:

// In your form component
const csrfToken = useMemo(() => crypto.randomUUID(), []);

const handleSubmit = async (data) => {
  await fetch("/api/submit", {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "X-CSRF-Token": csrfToken,
    },
    body: JSON.stringify(data),
  });
};

Common Pitfall

When debugging this, start by reproducing the exact error message. Slight variations in the error text can point to completely different root causes in Gatsby. If you're using Docker or a containerized setup, make sure the fix is reflected in both your local and production Dockerfiles.

Testing Your Changes

Run your test suite to make sure the fix doesn't introduce regressions. If you don't have tests covering this area, now is a good time to add a simple integration test. A quick manual smoke test across different browsers or environments can also catch edge cases your tests might miss.

Monitoring

Tools like [Bugsly](https://bugsly.dev) can catch these Gatsby errors in real time, giving you stack traces and context to fix issues faster.